Published Online: 21 January 2010
Page Count: 10
Zarr, Robert R.
Mechanical Engineer, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, MD
(Received 15 April 2009; accepted 24 October 2009)
An uncertainty analysis for steady-state thermal transmission properties determined by the National Institute of Standards and Technology (NIST) 1016 mm guarded-hot-plate apparatus is presented for fibrous-glass blanket and expanded polystyrene board. The uncertainties are presented for the guarded-hot-plate apparatus in the single-sided mode of operation covering specimen heat flows from 0.5 to 5 W. The relative expanded uncertainties for thermal resistance increase from 1 % to 3.5 % for thicknesses of 25.4 to 254 mm, respectively. Although these uncertainties have been developed for two thermal insulation materials, the results are indicative of other insulation materials measured at a mean temperature near 297 K (23.9°C). This assessment of uncertainties is of particular interest for users of ASTM C177-04 test method that operate similar apparatus at low heat flows (i.e., near or less than 1 W). Implications for laboratories that develop secondary standards from NIST calibrations are discussed.
Paper ID: JTE102462